The Hakka or Kejia are found in a broad belt across southern China. They speak a group of closely related dialects collectively known as the Hakka language which belongs to the Chinese family of languages. Hakka are one small part of the Han ethnic group of China, and currently thought to be about 35 million people, residing in Guangdong, Fujian, Jiangxi, Guangxi, Hunan, Sichuan Guizhou, Hainan and Taiwan.

foshelan wrote:Could anybody tell me about the relationship between the Hakka languages and the Yue languages?

Both are Chinese languages spoken in the Southern part of China. It is assumed that the current Chinese languages have a common close ancestor which sounded close to Hakka and/or Cantonese. During the centuries of migrations of the Han people from the north to the south, different migrates paths caused a diverges which finally resulted in the current family of languages.
Both Hakka and Cantonese that are now populating Guangdong province are believed to be originating from the north but they differ in migration route and arrival time.